Single-axis actuator, acoustic wave generator and its array

ABSTRACT

The present invention provides a single-axis actuator. The single-axis actuator includes: a substrate; a driving capacitor; an actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the actuating end and the substrate for effecting a parametric characteristic of the single-axis actuator to apply to an generation of an acoustic wave.

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

This application claims the benefit of U.S. Provisional Applications No. 62/931,926, filed on Nov. 7, 2019 and No. 63/065,692, filed on Aug. 14, 2020 in the United States Patent and Trademark Office, the disclosures of which are incorporated herein in their entirety by reference.

FIELD OF THE INVENTION

The invention relates to a single-axis actuator, and more particularly to an acoustic wave generator including the single-axis actuator.

BACKGROUND OF THE INVENTION

Traditionally, acoustic wave generators are driven by voice coil motors. The voice coil motors have large inertia issues, as well as size and power consumption issues. The voice coil speakers need different sizes for different sound frequency bands, so there will be several monomers with different sizes. However, MEMS (micro-electromechanical system) acoustic wave generators have advantages such as small form factor, low power consumption, and being easily integrated with a printed circuit board (PCB) and an application-specific integrated circuit (ASIC) on a PCB. Different actuation types are used for MEMS acoustic wave generators. Among them, electrostatic actuators are easy to fabricate. However, to completely replace the voice coil, the efficiency of electrical-to-mechanical energy conversion of the electrostatic actuators needs to be increased. Moreover, the traditional voice coil speaker has a magnetic force between the magnet and the voice coil. The magnetic force is distorted due to different gap distances between the magnet and the voice coil, so that the sound quality is affected. As the gap increases, more electromagnetic force is needed and more power is consumed to obtain a good low frequency response. In the prior art, the voice coil speaker, e.g. miniature headphone, is limited by its stroke limitation and cannot provide a larger stroke in the low frequency. Hence, the speaker has a poor response in the low frequency, and the sound of the speaker is broken due to excessive output in the high frequency. Furthermore, the periphery of the traditional membrane is fixed to other objects, and therefore, when the acoustic pressure is generated, the movement of the middle of the membrane is the most and that of the periphery of the membrane is small. In order to provide good low frequency response, the stroke of membrane must be increased, and this is why the large headphone has better low frequency response than the small one. Thus, it is very important to make a tiny loudspeaker with large membrane stroke for a high sound quality headphone.

SUMMARY OF THE INVENTION

The present invention discloses an acoustic wave generator including a single-axis actuator that overcomes the drawback in prior art. The single-axis actuator has a high efficiency of electrical-to-mechanical energy conversion and a large motion stroke. Multiple single-axis actuators can be adopted in the acoustic wave generator. When different DC offset voltages and the same acoustic driving signal are applied to the actuators, the plate of the acoustic wave generator is able to move along the out-of-plane direction and rotate along two in-plane directions to generate acoustic pressure according to the acoustic driving signal. Multiple single-axis actuators having different parametric characteristics can also increase the bandwidth and improve the frequency response of the acoustic wave generator. Unlike the traditional acoustic wave generator driven by voice coil motors, the frequency response of the proposed acoustic wave generator does not depend on the size of the acoustic wave generator. The acoustic wave generator of the present invention provides a long stroke up to 500 μm and consumes only microwatts of power, so that the acoustic wave generator has excellent low frequency response as well as being able to save more power. The present invention also provides an acoustic wave generator array with multi-balanced armatures.

In accordance with an aspect of the present invention, an acoustic wave generator is provided. The acoustic wave generator includes: a single-axis actuator including: a substrate; a driving capacitor; a first actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the first actuating end and the substrate, wherein the first pair of resilient elements are provided for determining a frequency response of the acoustic wave generator; and a plate mounted on and driven by the first actuating end to generate an acoustic wave.

In accordance with a further aspect of the present invention, an array including a plurality of the acoustic wave generators is provided.

In accordance with another aspect of the present invention, a single-axis actuator is provided. The single-axis actuator includes: a substrate; a driving capacitor; an actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the actuating end and the substrate for effecting a parametric characteristic of the single-axis actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

The details and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed descriptions and accompanying drawings.

FIG. 1 shows a top view of an embodiment of an out-of-plane motion motor of the present invention.

FIG. 2 shows a sectional schematic diagram of a cut view of the out-of-plane motion motor along the section line A-A′ in FIG. 1.

FIG. 3 shows a top view of another embodiment of the out-of-plane motion motor of the present invention.

FIG. 4 shows a three dimensional diagram of the out-of-plane motion motor shown in FIG. 3.

FIG. 5 shows a schematic diagram of a single-axis actuator of the present invention.

FIG. 6 shows a partial schematic diagram of a single-axis actuator wafer of the present invention.

FIG. 7 shows an exploded view of an out-of-plane motion actuator of the present invention.

FIG. 8 shows a three dimensional diagram of the out-of-plane motion actuator of the present invention.

FIG. 9 shows a schematic diagram of an embodiment of a single-sided single-axis actuator of the present invention.

FIG. 10 shows a schematic diagram of an actuation of the single-sided single-axis actuator of the present invention.

FIG. 11 shows a schematic diagram of an embodiment of a double-sided single-axis actuator of the present invention.

FIG. 12 shows a schematic diagram of an actuation of the double-sided single-axis actuator of the present invention.

FIG. 13 shows a schematic diagram of another actuation of the double-sided single-axis actuator of the present invention.

FIG. 14 shows a schematic diagram of another actuation of the double-sided single-axis actuator of the present invention.

FIG. 15 shows a planar schematic diagram of a displacement magnifying mechanism of the present invention.

FIG. 16 is the schematic view of another embodiment of the single-axis actuator of the present invention.

FIG. 17 is the schematic view of another embodiment of the single-axis actuator of the present invention.

FIG. 18 is a schematic sectional view of the single-axis actuator along the section line C-C′ in FIGS. 5 and 16.

FIG. 19 is a schematic view of the acoustic wave generator of the present invention.

FIG. 20 is a schematic view of another embodiment of the acoustic wave generator of the present invention.

FIG. 21A shows an example in which the center of gravity of the first glass aligns the center of gravity of the single-axis actuator without the T-bar and the fulcrum hinge.

FIG. 21B shows an example in which the center of gravity of the first glass does not align the center of gravity of the single-axis actuator without the T-bar and the fulcrum hinge.

FIG. 21C shows an embodiment of the present invention with both the fulcrum hinge and the T-bar.

FIGS. 22A and 22B show the schematic top view of two additional embodiments of the fulcrum hinge of the present invention.

FIG. 23A shows the schematic view of the acoustic wave generator array of the present invention.

FIG. 23B shows the schematic view of another embodiment of the acoustic wave generator array of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of the preferred embodiments of this invention are presented herein for the purposes of illustration and description only; they are not intended to be exhaustive or to be limited to the precise form disclosed.

Please refer to FIG. 1 and FIG. 2, wherein FIG. 1 is a top view of an out-of-plane motion motor of an embodiment of the present invention, and FIG. 2 is a sectional schematic diagram of a cut view of the out-of-plane motion motor along the section line A-A′ in FIG. 1. FIG. 1 and FIG. 2 show that a first single-axis motion motor 7045-1 and a second single-axis motion motor 7045-2 configure on a base plate surface 852 of a base plate 851 of the out-of-plane motion motor 7040. As a mechanism that can produce a planar motion, a motion direction of an actuating end 855 of a single-axis actuator 854 is substantially parallel to a normal direction of the base plate surface 852. The normal direction for FIG. 1 is a direction that perpendicular to the drawing surface, and the normal direction for FIG. 2 is an upward direction. A carried object 5000′ is carried on the actuating end 855 of a single-axis actuator 854 in the single-axis motion motor 7045-1, wherein the carried object 5000′ can be a reflector, a reflecting mirror, a lens, a semi-reflecting mirror, etc. Because of the high-speed response performance of a micro-electromechanical system, the carried object 5000′ of the present invention can also be a vibrating membrane. According to the configuring positions of the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2, the carried object 5000′ can not only be moved upwards and downwards in parallel, but also can be rolled. Therefore, the carried object 5000′ can have more displacement in the out-of-plane direction caused by the single-axis motion motors 7045-1 and 7045-2 of the present invention. In addition, because there is usually no need for other structures underneath the carried object 5000′ to support the carried object 5000′, a redundant space 852′ is formed between the carried object 5000′ and the base plate surface 852, where the electronic element 6009 can be configured therein to save the overall equipment space. In addition, in order to facilitate the handling of the out-of-plane motion motor 7040, a base plate frame 853 is formed on the periphery of the base plate 851 substantially parallel to the direction of the normal line of the base plate surface 852. That is, the periphery of the base plate 851 is thickened to facilitate the handling by a robotic arm (figure not shown).

Please refer to FIG. 3 and FIG. 4, wherein FIG. 3 is a top view of the out-of-plane motion motor according to another embodiment of the present invention, and FIG. 4 is a three dimensional diagram of the out-of-plane motion motor shown in FIG. 3. It can be seen in FIG. 3 and FIG. 4 that two single-axis motion motors 7045-1 and 7045-2 are no longer only configured on both sides on the base plate surface 852, but additional single-axis motion motors are further cooperatively configured on the four corners on the base plate surface 852, which include a first single-axis motion motor 7045-1, a second single-axis motion motor 7045-2, a third single-axis motion motor 7045-3 and a fourth single-axis motion motor 7045-4, and these four single-axis motion motors form the out-of-plane motion motor 7040 according to another embodiment of the present invention. Therefore, in the embodiment shown in FIG. 3 and FIG. 4, the carried object 5000′ can not only be moved upwards and downwards and parallel to the normal direction of the base plate surface 852, but also have pitching motion by synchronously controlling the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2 and/or synchronously controlling the third single-axis motion motor 7045-3 and the fourth single-axis motion motor 7045-4, and thus the carried object 5000′ totally has three degrees-of-freedom. Specifically, the four single-axis motion motors can be controlled to generate different displacements respectively, so that the carried object 5000′ can have translational, rolled and pitched motions. The number and the configuring positions of the single-axis actuators in FIG. 3 and FIG. 4 are not absolute, and can be altered according to actual demands. For example, because three points can form a plane, in theory, only three single-axis actuators are needed to achieve three degrees-of-freedom movements, i.e. translation of up-and-down and rotations of roll and pitch.

Please refer to FIG. 5, which is a schematic diagram of a single-axis actuator according to one embodiment of the present invention. A detailed structure of the single-axis actuator 854 is showed in FIG. 5. The single-axis actuator 854 mainly includes a movable electrode structure 500 and fixed electrode structures including a first fixed electrode structure 300 and a second fixed electrode structure 610. The movable electrode structure 500 has a keel 510 and comb fingers 520 fixed on the keel 510, and the first fixed electrode structure 300 has comb fingers 320 fixed on a supporting arm 1200. A sensing capacitor 600 including the second fixed electrode structure 610 and the movable electrode structure 500 is formed for sensing a capacitance value therebetween, and a distance between the movable electrode structure 500 and the first fixed electrode structure 300 is obtained through the conversion of the measured capacitance value. The first fixed electrode structure 300 is indirectly fixed by a third anchor 803 through the supporting arm 1200, and the second fixed electrode structure 610 is fixed by a fourth anchor 804. The movable electrode structure 500 is indirectly fixed by a second anchor 802 through two constraining hinges 900 which can prevent the movement of the movable electrode structure 500 from exceeding the allowable range. An embodiment of the actuating end 855 is a T-bar 1100, wherein the T-bar 1100 is fixed on the movable electrode structure 500, and is indirectly fixed by a first anchor 801 through two main hinges 400. A first center point 450 is formed between the T-bar 1100 and the main hinges 400 at the two sides of the T-bar 1100. The main hinges 400 are used to carry the most weight of the T-bar 1100 and the weight of the movable electrode structure 500, and bear an elastic restoring force of returning the T-bar 1100 when the electrostatic force between the movable electrode structure 500 and the first fixed electrode structure 300 disappears. In order to avoid the T-bar 1100 and the carried object 5000′ from separating by a lateral force applied to the T-bar 1100 or the carried object 5000′, a fulcrum hinge 700 is configured on a vertical portion of the T-bar 1100. The fulcrum hinge 700 can deform laterally to absorb the aforementioned lateral force. In addition, in order to maintain a parallelism of a head portion of the T-bar 1100, i.e. the parallelism between the T-bar 1100 and the base plate surface 852, the fulcrum hinge 700 can be designed to be undeformable under forces applied in the normal direction (Y direction in FIG. 5) of the base plate surface 852.

Please refer to FIG. 6, which is a partial schematic diagram of an actuator wafer of the present invention. The actuator wafer 20000 includes a plurality of single-axis actuating structures. FIG. 6 shows a part of an actuator wafer 20000 containing one single-axis actuator structure 10000. After the single-axis actuator structure 10000 is cut from the actuator wafer 20000, the single-axis actuator 854 is obtained. The single-axis actuating structure 10000 of the micro-electromechanical system is manufactured using semiconductor process technology, which can form a plurality of the single-axis actuators on a piece of the actuator wafer 20000, and then the actuator wafer 20000 is cut into the plurality of the single-axis actuators. In order to avoid the trouble caused by process residues and debris, a cavity 200 is formed below the comb fingers 520 of the movable electrode structure 500 and the comb fingers 320 of the first fixed electrode structure 300 in the present invention, so that the residues and debris can be discharged from the cavity 200 or can be at least settled in the cavity 200 to keep away from each fingers. For the same reason, a third cavity 20500 is formed under the T-bar 1100 to facilitate the discharge of the residues and debris generated by the manufacturing process under the T-bar 1100.

Please refer to FIG. 7 and FIG. 8, wherein FIG. 7 is an exploded view of an out-of-plane motion actuator of the present invention, and FIG. 8 is a three dimensional diagram of the out-of-plane motion actuator of the present invention. FIG. 7 and FIG. 8 show that the single-axis actuator 854 formed by cutting from the single-axis actuating structure 10000 in FIG. 6 is configured on an actuator connection seat 6001′ to form the single-axis motion motor 7045. In FIGS. 5, 7 and 8, it can be seen that the single-axis actuator 854 includes a substrate 100, to which the actuating end 855, the first anchor 801, the second anchor 802, the third anchor 803 and the fourth anchor 804 are connected. A control chip 6008 can be further configured on the actuator connection seat 6001′ and adjacent to the single-axis actuating structure 10000 to control the single-axis actuating structure 10000 nearby. The actuator connection seat 6001′ is fixed on the base plate 6003 by clamps 6004. Contact pads 6006 of the actuator connection seat 6001′ are electrically connected to metal pads 6007 on the base plate surface 6005, causing the electronic signal to be transmitted to the control chip 6008 and each of the comb fingers 520, 320 through the contact pads 6006, the metal pads 6007 and the circuit in the actuator connection seat 6001′ (figure not shown) to form a complete route of the electronic signal for the out-of-plane motion actuator 6000. According to requirements, other electrical connection pads 6007′ can be further configured on the base plate surface 6005 to electrically connect to other electronic elements (figure not shown). The metal pads 6007 and the electrical connection pads 6007′ present, but are not limited to, one-to-one correspondence relationship. For the actuator connection seat 6001′, the metal pads 6007 or the electrical connection pads 6007′ can be used, that is, the position of the actuator connection seat 6001′ can be determined according to the actual demand, such as a size of the carried object 5000′.

Please refer to FIG. 9 and FIG. 10, wherein FIG. 9 is a schematic diagram of a motor having only one single-axis actuator (or called a single-sided single-axis-actuator motor) according to an embodiment of the present invention, and FIG. 10 is a schematic diagram of an actuation of the single-sided single-axis-actuator motor of the present invention. FIG. 9 and FIG. 10 show that one side of the single-sided single-axis-actuator motor 8000 is a fulcrum structure 7000, and the opposite side of the single-sided single-axis-actuator motor 8000 is the single-axis motion motor 7045 of the present invention. Therefore, the fulcrum structure 7000 and the single-axis motion motor 7045 are respectively located at the two sides, the left and the right sides or the front and the rear sides, of the carried object 5000′. Of course, the fulcrum structure 7000 and the single-axis motion motor 7045 can also be respectively located at the diagonal sides of the carried object 5000′. Only a slight rotation of the carried object 5000′ is allowed on the fulcrum structure 7000. The fulcrum structure 7000 usually has, but is not limited to, a structure such as fulcrum hinge 700 (as shown in FIG. 5) to absorb shear stress caused by improper external forces. When the single-axis motion motor 7045 moves upwards or downwards, the position of the carried object 5000′ connected thereto is also moved upwards or downwards along with the single-axis motion motor 7045. FIG. 10 shows the position of the carried object 5000′ connecting to the single-axis motion motor 7045 while the single-axis motion motor 7045 moves upwards to a top dead center (TDC) or downwards to a bottom dead center (BDC). Furthermore, in order to protect the carried object 5000′, a protective structure 5000″ mounted above the carried object 5000′ is provided in the present invention. The protective structure 5000″ is usually supported by a supporting wall 902 of an accommodating base 910. The out-of-plane motion motor 7040 (figure not shown) including the plurality of single-axis motion motors 7045 is configured on the accommodating bottom plate 901 of the accommodating base 910.

Please refer to FIG. 11, FIG. 12 and FIG. 13, wherein FIG. 11 is a schematic diagram of an embodiment of a two-sided single-axis-actuator motor of the present invention, FIG. 12 is a schematic diagram of an actuation of the two-sided single-axis-actuator motor of the present invention, and FIG. 13 is a schematic diagram of another actuation of the two-sided single-axis-actuator motor of the present invention. FIG. 11, FIG. 12 and FIG. 13 show that one side of the two-sided single-axis-actuator motor 9000 is the first single-axis motion motor 7045-1 of the present invention, and the opposite side of the two-sided single-axis-actuator motor 9000 is the second single-axis motion motor 7045-2 of the present invention. FIG. 12 shows the position of the two ends of the carried object 5000′ respectively connecting to the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2 while the first single-axis motion motor 7045 moves up to its top dead center, and the second single-axis motion motor 7045-2 moves down to its bottom dead center at the same time. Contrary to FIG. 12, FIG. 13 shows the position of the two ends of the carried object 5000′ respectively connecting to the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2 while the first single-axis motion motor 7045 moves down to its bottom dead center, and the second single-axis motion motor 7045-2 moves up to its top dead center at the same time. However, in the implementation state of some actuators, they can only move upwards or downwards, and then return to their original relatively low or relatively high positions. If the embodiments of FIG. 12 and FIG. 13 are understood as the actuator that can only move upwards, it can be understood in FIG. 12 that the second single-axis motion motor 7045-2 remains stationary, while the first single-axis motion motor 7045-1 moves upwards, for example, to its top dead center. In contrast, it can be understood in FIG. 13 that the first single-axis motion motor 7045-1 remains stationary, while the second single-axis motion motor 7045-2 moves upwards. Similarly, if the embodiments of FIG. 12 and FIG. 13 are understood as the actuator that can only move downwards, it can be understood in FIG. 12 that the first single-axis motion motor 7045-1 remains stationary, while the second single-axis motion motor 7045-2 moves downwards, for example, to its bottom dead center. In contrast, it can be understood in FIG. 13 that the second single-axis motion motor 7045-2 remains stationary, while the first single-axis motion motor 7045-1 moves downwards.

Please refer to FIG. 14, which is a schematic diagram of another actuation of the double-sided single-axis actuator of the present invention. When the single-axis actuator can only move upwards or downwards, the present invention can still achieve both translational and rolling movement according to the difference of the moving amplitude of the two actuators. Please see the two downward hollow arrows in FIG. 14, when the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2 can only move downwards, the downward movement amount of the first single-axis motion motor 7045-1 is larger, and the downward movement amount of the second single-axis motion motor 7045-2 is smaller. Similarly, please see the two upward hollow arrows in FIG. 14, when the first single-axis motion motor 7045-1 and the second single-axis motion motor 7045-2 can only move upwards, the upward movement amount of the first single-axis motion motor 7045-1 is smaller, and the upward movement amount of the second single-axis motion motor 7045-2 is larger.

Please refer to FIG. 15, which is a planar schematic diagram of a displacement magnifying mechanism of the present invention. In order to increase the moving distance, a displacement magnifying mechanism 4000 can be used in the present invention. The displacement magnifying mechanism 4000 of the present invention includes a first lever L1 and a second lever L2, wherein an end of the first lever L1 is a first lever fulcrum L1 f, and the other end of the first lever L1 connects to the second lever L2 through a second contact point L2 c. The point of application of the out-of-plane motion actuator 6000 is at a first contact point L1 c. Because the first contact point L1 c is located between the first lever fulcrum L1 f and the second contact point L2 c, the moving amplitude of the second contact point L2 c is larger than that of the first contact point L1 c, when the out-of-plane motion actuator 6000 moves. Similarly, because the second contact point L2 c is located between a second lever fulcrum L2 f and a carrying point L2 m, the moving amplitude of the carrying point L2 m is larger than that of the second contact point L2 c, when the second contact point L2 c moves. Therefore, the displacement of the out-of-plane motion actuator 6000 can be magnified, so that the displacement of the carried object 5000′ is larger than that of the out-of-plane motion actuator 6000. If a more significant amplification effect is desired, a first distance a is smaller than a second distance b, and a third distance c is smaller than a fourth distance d, wherein the first distance a is a distance between the first contact point L1 c and the first lever fulcrum L1 f, the second distance b is a vertical distance between the first contact point L1 c and the second contact point L2 c, the third distance c is a distance between the second contact point L2 c and the second lever fulcrum L2 f, and the fourth distance d is a vertical distance between the second contact point L2 c and the carrying point L2 m. Accordingly, although the piezoelectric material in the prior art uses a displacement amplifying mechanism to enlarge its moving distance, the original displacement distance of the actuator of the present invention is much greater than that of the piezoelectric material, and thus the overall displacement distance achieved by the present invention is still far greater than the displacement distance of the piezoelectric material after being amplified by the displacement amplifying mechanism.

In another embodiment, the single-axis actuator of the present invention is shown in FIG. 16. In FIG. 16, the width of the actuating end 61200 of the single-axis actuator 8541 for carrying the object is the same as that of the substrate 100, and apart from the elements shown in FIG. 5, the single-axis actuator 8541 further includes at least one pair of resilient elements (three pairs of resilient elements are shown in FIG. 16) connecting the actuating end 61200 and the substrate 100, which are a first resilient element 61300 and a second resilient element 61400. The first resilient element 61300 and the second resilient element 61400 are respectively disposed on the first side and the second side of the fulcrum hinge 700. Each of the first resilient element 61300 and the second resilient element 61400 of the at least one pair of resilient elements includes a wire (figure not shown), wherein an end of the wire connects to a pad 61500 of the actuating end 61200, and an opposite end of the wire connects to a pad of a pad-anchor 61600 of the substrate 100. Therefore, the substrate 100, the first resilient element 61300/the second resilient element 61400 and the actuating end 61200 are electrically connected. In this embodiment, the actuating end 61200 is a T-bar, and the T-bar connects to the substrate 100 through the fulcrum hinge 700 and the main hinge 400 having the first side and the second side. In a further embodiment, the single-axis actuator 8542 does not have a main hinge, as shown in FIG. 17.

The first resilient element 61300 and the second resilient element 61400 of the single-axis actuator 8541 can be a soft spring, which does not provide the main rigid support. The first resilient element 61300 and the second resilient element 61400 of the single-axis actuator 8541 can also be a material providing the rigid support. The stiffness of the first resilient element 61300 and the second resilient element 61400 are lower than that of the main hinge 400. Therefore, the first resilient element 61300 and the second resilient element 61400 can be used to generate a parametric characteristic of the single-axis actuator 8541, such as an electrical or heat conductivity of the first resilient element 61300 and the second resilient element 61400, or a stiffness related to a vibrational response. For example, the first resilient element 61300 and the second resilient element 61400 conduct heat of the actuating end 61200 to the substrate 100.

Please refer to FIGS. 5 and 16, two embodiments of the single-axis actuators 854, 8541 and are respectively shown, and FIG. 18 is a schematic sectional view of the single-axis actuators 854, 8541 along the section line C-C′ in FIGS. 5 and 16. It is seen from FIG. 18 that the substrate 100 of the single-axis actuators 854, 8541 has the cavity 200 and an electronic element 110. The electronic element 110 disposed on the substrate 100 represents the integration of all the motion control electronic components and circuits on the substrate 100. Therefore, the actuating end 61200 in FIG. 16 may be driven by the electronic element 110 for carrying and moving the object. The substrate 100 of the single-axis actuators 854, 8541 has a front surface 120 and a rear surface 130, and the cavity 200 penetrates through the front surface 120 and the rear surface 130 in the Z-direction as defined in FIGS. 5 and 16. As shown in FIGS. 5 and 16, the single-axis actuators 854, 8541 may have a comb type driving capacitor 61800 including a fixed electrode structure 300 fixed on the substrate 100 and a movable electrode structure 500 connected to the main hinge 400, and the comb type driving capacitor 61800 drives the movement of the respective actuating end 855, 61200. The size of the cavity 200 has to be sufficiently large to completely remove the residual materials from processing; a square with side length slightly more than 10 microns would be sufficiently large. To put it another way, if one looks upwards from the cavity 200 on the rear surface 130 and sees any comb finger, then the cavity 200 is sufficiently large. Without the cavity 200, the comb fingers 320, 520 in FIGS. 5 and 16 have to be sparsely arranged to remove the residual materials. But when the comb fingers 320, 520 are sparsely arranged, the efficiency of electrical-to-mechanical energy conversion is low. In other words, the voltage applied between the first fixed electrode structure 300 and the movable electrode structure 500 has to be high. Hence, the cavity 200 allows the removal of residual process contaminants and the improvement of the efficiency of electrical-to-mechanical energy conversion. From another point of view, the cavity 200 allows the embodiments of single-axis actuators 854, 8541 to have a larger motion stroke compared to the single-axis actuators in prior art for the same voltage applied.

The single-axis actuator of the present invention has a large motion stroke, the robustness of impact, the easy removal of residual process contaminants, an improvement of the efficiency of electrical-to-mechanical energy conversion and the off-axis motion decoupling of movable comb structure.

The single-axis actuator of the present invention can be applied in an acoustic wave generator. Please refer to FIG. 19, which is a schematic view of the acoustic wave generator 60000 of the present invention. The acoustic wave generator 60000 of the present invention includes at least one single-axis actuator and a plate 62000 carried thereon. The single-axis actuator can carry the plate from the positions below the edges of the plate 62000, as shown in FIG. 19, or from the positions below the four corners of the plate 62000, as shown in FIG. 20. The plate 62000 of the acoustic wave generator 60000 of the present invention is stiff, does not deform and is not fixed with any components around it, and the entire plate 62000 can be moved by the single-axis actuator to generate the acoustic pressure. Specifically, the overall movement range of the plate 62000 of the present invention is the same, and unlike the traditional voice coil speaker, the movement of the middle of the membrane is the most and that of the periphery of the membrane is small. The material of the plate 62000 of the present invention can be a semiconductor material, metal material, etc. The single-axis actuator of the acoustic wave generator 60000 can use the single-axis actuator 854 of FIG. 5, the single-axis actuator 8541 of FIG. 16 and the single-axis actuator 8542 of FIG. 17, and the embodiment in FIG. 19, the single-axis actuator 8541 of FIG. 16 is used. The actuating end 61200 of the single-axis actuator 8541 can carry the plate 61200, and the driving capacitor 61800 can drive the movement of the actuating end 61200, so as to move the plate to generate an acoustic wave.

In the present invention, the fulcrum hinge 700 is designed to prevent the plate 62000 from peeling off from the actuating end 61200 when there is a shear force at a boundary surface between the plate 62000 and the actuating end 61200. In general, the actuating end 61200 carries and moves an object, and the fulcrum hinge 700 prevents the object from peeling off from the actuating end 61200. FIG. 21A shows an example in which the center of gravity of the plate 62000 aligns the center of gravity of the single-axis actuator without the T-bar (i.e. the actuating end 61200) and the fulcrum hinge. In comparison, FIG. 21B shows an example in which the center of gravity of the plate 62000 does not align the center of gravity of the single-axis actuator without the T-bar and the fulcrum hinge. In FIG. 21B, the stress concentrates on the circled area, and thus, a torque is produced. FIG. 21C shows an embodiment of the present invention with both the fulcrum hinge 700 and the actuating end 61200 to avoid the problem arising from FIG. 21B. The fulcrum hinge 700 has low stiffness in the X-direction shown in FIG. 16, but high stiffness in the Y-direction and Z-direction. In other words, the stiffness in the Y-direction k_(Y) is much greater than the stiffness in the X-direction k_(X), i.e. k_(Y)>>k_(X), and the stiffness in the Z-direction k_(Z) is also much greater than the stiffness in the X-direction k_(X), i.e. k_(Z)>>k_(X). High stiffness in the Y-direction is necessary to avoid the decrease of displacement in the Y-direction. One skilled in the art can design a variety of fulcrum hinges to meet the requirements. FIGS. 22A and 22B show the schematic top view of two embodiments of the fulcrum hinge in addition to the fulcrum hinge 700 shown in FIG. 16 or 21C. For the case without the fulcrum hinge 700, an external X-directional (as defined in FIG. 16) force applied to the object carried by the actuating end may generate a shear force and a moment at the boundary surface between the object and the actuating end 61200. The large shear force and/or the moment may cause the object to peel off from the surface of the actuating end 61200. For the case with the fulcrum hinge 700, the external X-directional force applied to the object may lead to a deformation of the fulcrum hinge 700 to reduce the shear force and the moment at the boundary surface between the object and the actuating end 61200. In some circumstances, the fulcrum hinge 700 can be omitted if the shear force is negligible.

In the embodiment of the acoustic wave generator 60000 shown in FIG. 19, there are two single-axis actuators 8541. As the displacement of each of the single-axis actuators 8541 is independently changed, the plate 62000 can be driven to move upwardly and downwardly in the out-of-plane direction horizontally or tilt in the out-of-plane direction. When the same DC signals and the same AC signals (the acoustic signal) are applied to the two single-axis actuators 8541, the two single-axis actuators 8541 can parallelly move the plate 62000 upwardly and downwardly, so as to generate the acoustic wave. When the different DC signals and the same AC signals (the acoustic signal) are applied to the two single-axis actuators 8541, the two single-axis actuators 8541 can move the plate 62000 with a tilt angle upwardly and downwardly, so as to generate the acoustic wave toward to a direction normal to the tilt direction. In other words, the plate 62000 can perform the rotational movement according to the variation of the DC signals, and perform the out-of-plane translational movement according to the variation of the AC signals. The plate 62000 can also be kept at a specific rotation angle or positioned at a specific out-of-plane displacement position.

A single single-axis actuator 8541 can also be used in the acoustic wave generator 60000. In this embodiment, one single-axis actuator 8541 is replaced by a fixed support allowing a slight rotation of the plate 62000 around an in-plane axis along the extension direction of the fixed support. There can be other designs for an acoustic wave generator 60000 using a single single-axis actuator 8541, including different positions and orientations of the single single-axis actuator 8541. One skilled in the art can design a variety of such acoustic wave generators to meet the application needs.

Three single single-axis actuators 8541 can also be used in the acoustic wave generator 60000 to achieve three-degree-of-freedom movements as mentioned above. As the displacement of each of the single single-axis actuators 8541 is independently changed, the plate 62000 can be driven to move upwardly and downwardly in the out-of-plane direction with or without a single-axis tilt or in the out-of-plane direction with a dual-axis tilt. That is to say, in the acoustic wave generator 60000 including three single single-axis actuators 8541, the plate 62000 can perform the single-axis rotational or the dual-axis rotational movement according to the variation of the DC signals, and perform the out-of-plane translational movement according to the variation of the AC signals to achieve three-degree-of-freedom movements. The plate 62000 can also be kept at a specific rotation angle, positioned at a specific out-of-plane displacement position or programmed to perform a specific scan trajectory motion.

Four single single-axis actuators 854 can also be used in the acoustic wave generator 60000, as shown in FIG. 20, to achieve three-degree-of-freedom movements as mentioned above. As the displacement of each of the single single-axis actuators 854 is independently changed, the plate 62000 can be driven to move upwardly and downwardly in the out-of-plane direction with or without a single-axis tilt or in the out-of-plane direction with a dual-axis tilt. That is to say, in the acoustic wave generator 60000 including four single single-axis actuators 854, the plate 62000 can perform the single-axis rotational or the dual-axis rotational movements according to the variation of the DC signals, and perform the out-of-plane translational movement according to the variation of the AC signals to achieve three-degree-of-freedom movements. The plate 62000 can also be kept at a specific rotation angle, positioned at a specific out-of-plane displacement position or programmed to perform a specific scan trajectory motion. The single single-axis actuator 854 of FIG. 5, the single single-axis actuator 8541 of FIG. 16 and the single single-axis actuator 8542 of FIG. 17 can be optionally or mixedly used in the acoustic wave generator 60000 of the present invention.

In the acoustic wave generator of the present invention, when the plate is moved upwardly and downwardly in the out-of-plane direction, in the out-of-plane direction with the single-axis tilt or in the out-of-plane direction with the dual-axis tilt, the acoustic pressure is generated by the vibrational frequency of the plate, and the magnitude of the acoustic pressure is determined by the vibrational response of the single-axis actuator. The parameters determining the vibrational response of the single-axis actuator include the mass (m) of the plate, the stiffness (k) and the damping (δ) of the at least one pair of the resilient elements (i.e. the first resilient element 61300 and the second resilient element 61400 in FIG. 16). The damping (δ), the stiffness (k) and the mass (m) correspond to the resistance (R), the inductance (L) and the capacitance (C) in the circuit. Therefore, the plate of the present invention can have an appropriate number and size of holes to decrease the damping (δ). Furthermore, the present invention can use the mass (m) of the plate and the stiffness (k) of the resilient element to determine the frequency response of the acoustic wave generator. For example, the stiffness of a pair of the resilient elements is lower than that of three pairs of the resilient elements, and the acoustic wave generator having one pair of the resilient element has better base response. Furthermore, the stiffness of the single-axis actuator is k, the stiffness of the acoustic wave generator using two single-axis actuators is 2k, and so on. Accordingly, the more the single-axis actuators are used in the acoustic wave generator, the larger the stiffness (k) of acoustic wave generator is, that is, the higher the equivalent stiffness (k) is. Therefore, it is easier to push the plate under the condition that the mass (m) of the plate is constant, so that the acoustic wave generator has a larger bandwidth. Hence, a system having parameters 4k and m is equivalent to a system having parameters k and m/4.

Because the single-axis actuator of the present invention has large motion stroke, the acoustic wave generator provides a long stroke up to 500 μm and consumes only microwatts of power, so that the acoustic wave generator has excellent low frequency response as well as being able to save more power.

The plurality of the acoustic wave generators of the present invention can form an acoustic wave generator array to achieve functions of amplifying the sound pressure and strengthening the low frequency response, as shown in FIGS. 23A and 23B. Please refer to FIG. 23A, the acoustic wave generator array 70000 can be formed by a plurality of the acoustic wave generators 60000 having two single-axis actuators 8541. Please refer to FIG. 23B, the acoustic wave generator array 70000 can be formed by a combination of the acoustic wave generators 60000 having two single-axis actuators 8541 and the acoustic wave generators 60000′ having four single-axis actuators 8541. The acoustic wave generator array 70000 of the present invention has multi-balanced armatures. In FIGS. 23A and 23B, each of the acoustic wave generators 60000, 60000′ in the acoustic wave generator array 70000 can generate the acoustic wave in different direction, and the frequency response of each of the acoustic wave generators 60000, 60000′ can be complementary to generate a larger bandwidth and improve the overall frequency response of the array.

Embodiments

1. An acoustic wave generator, including: a single-axis actuator including: a substrate; a driving capacitor; a first actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the first actuating end and the substrate, wherein the first pair of resilient elements are provided for determining a frequency response of the acoustic wave generator; and a plate mounted on and driven by the first actuating end to generate an acoustic wave. 2. The acoustic wave generator according to Embodiment 1, further including a second single-axis actuator having a second actuating end, wherein the plate is also mounted on and driven by the second actuating end. 3. The acoustic wave generator according to Embodiment 1 or 2, further including a second, a third and a fourth single-axis actuators having a second, a third and a fourth actuating ends respectively, wherein the plate is also mounted on and driven by the second, the third and the fourth actuating ends. 4. The acoustic wave generator according to any one of Embodiments 1-3, wherein each of the first pair of resilient elements includes a wire electrically connected to a pad on the first actuating end. 5. The acoustic wave generator according to any one of Embodiments 1-4, wherein each of the first pair of resilient elements is electrically connected to a pad-anchor on the substrate. 6. The acoustic wave generator according to any one of Embodiments 1-5, wherein the first actuating end is a T-bar, and the plate include a plurality of holes. 7. The acoustic wave generator according to any one of Embodiments 1-6, wherein the T-bar is connected to the substrate through a fulcrum hinge having a first and a second sides, a first resilient element of the first pair of resilient elements is disposed on the first side of the fulcrum hinge, and a second resilient element of the first pair of resilient elements is disposed on the second side of the fulcrum hinge. 8. The acoustic wave generator according to any one of Embodiments 1-7, wherein the fulcrum hinge is configured to prevent the plate from peeling off from the T-bar when there is a shear force at a boundary surface between the plate and the T-bar. 9. An array including a plurality of the acoustic wave generators according to any one of Embodiments 1-8. 10. A single-axis actuator, including: a substrate; a driving capacitor; an actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the actuating end and the substrate for effecting a parametric characteristic of the single-axis actuator. 11. The single-axis actuator according to Embodiment 10, wherein the parametric characteristic is an electrical or heat conductivity of the first pair of resilient elements, or a stiffness related to a vibrational response. 12. The single-axis actuator according to Embodiment 10 or 11, wherein when the single-axis actuator is applied in an acoustic wave generator, the vibrational response determines a magnitude of an acoustic pressure. 13. The single-axis actuator according to any one of Embodiments 10-12, wherein the substrate has a front surface and a rear surface, and a cavity penetrates through the front and the rear surfaces. 14. The single-axis actuator according to any one of Embodiments 10-13, wherein the substrate has an electronic element. 15. The single-axis actuator according to any one of Embodiments 10-14, wherein each of the first pair of resilient elements includes a wire electrically connected to a pad on the actuating end. 16. The single-axis actuator according to any one of Embodiments 10-15, wherein each of the first pair of resilient elements is electrically connected to a pad-anchor on the substrate. 17. The single-axis actuator according to any one of Embodiments 10-16, wherein the actuating end is a T-bar. 18. The single-axis actuator according to any one of Embodiments 10-17, wherein the T-bar is connected to the substrate through a fulcrum hinge having a first and a second sides, a first resilient element of the first pair of resilient elements is disposed on the first side of the fulcrum hinge, and a second resilient element of the first pair of resilient elements is disposed on the second side of the fulcrum hinge. 19. The single-axis actuator according to any one of Embodiments 10-18, wherein the fulcrum hinge is configured to prevent an object carried by the actuating end from peeling off from the T-bar when there is a shear force at a boundary surface between the object and the T-bar. 20. The single-axis actuator according to any one of Embodiments 10-19, wherein the driving capacitor is a comb-type driving capacitor including a fixed electrode structure fixed to the substrate and a movable electrode structure connected to the fulcrum hinge.

It is contemplated that modifications and combinations will readily occur to those skilled in the art, and these modifications and combinations are within the scope of this invention. 

What is claimed is:
 1. An acoustic wave generator, comprising: a single-axis actuator including: a substrate; a driving capacitor; a first actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the first actuating end and the substrate, wherein the first pair of resilient elements are provided for determining a frequency response of the acoustic wave generator; and a plate mounted on and driven by the first actuating end to generate an acoustic wave.
 2. The acoustic wave generator as claimed in claim 1, further comprising a second single-axis actuator having a second actuating end, wherein the plate is also mounted on and driven by the second actuating end.
 3. The acoustic wave generator as claimed in claim 1, further comprising a second, a third and a fourth single-axis actuators having a second, a third and a fourth actuating ends respectively, wherein the plate is also mounted on and driven by the second, the third and the fourth actuating ends.
 4. The acoustic wave generator as claimed in claim 1, wherein each of the first pair of resilient elements includes a wire electrically connected to a pad on the first actuating end.
 5. The acoustic wave generator as claimed in claim 1, wherein each of the first pair of resilient elements is electrically connected to a pad-anchor on the substrate.
 6. The acoustic wave generator as claimed in claim 1, wherein the plate include a plurality of holes, and the first actuating end is a T-bar.
 7. The acoustic wave generator as claimed in claim 6, wherein the T-bar is connected to the substrate through a fulcrum hinge having a first and a second sides, a first resilient element of the first pair of resilient elements is disposed on the first side of the fulcrum hinge, and a second resilient element of the first pair of resilient elements is disposed on the second side of the fulcrum hinge.
 8. The acoustic wave generator as claimed in claim 7, wherein the fulcrum hinge is configured to prevent the plate from peeling off from the T-bar when there is a shear force at a boundary surface between the plate and the T-bar.
 9. An array comprising a plurality of the acoustic wave generators as claimed in claim
 1. 10. A single-axis actuator, comprising: a substrate; a driving capacitor; an actuating end driven by the driving capacitor; and a first pair of resilient elements connecting the actuating end and the substrate for effecting a parametric characteristic of the single-axis actuator.
 11. The single-axis actuator as claimed in claim 10, wherein the parametric characteristic is an electrical or heat conductivity of the first pair of resilient elements, or a stiffness related to a vibrational response.
 12. The single-axis actuator as claimed in claim 11, wherein when the single-axis actuator is applied in an acoustic wave generator, the vibrational response determines a magnitude of an acoustic pressure.
 13. The single-axis actuator as claimed in claim 10, wherein the substrate has a front surface and a rear surface, and a cavity penetrates through the front and the rear surfaces.
 14. The single-axis actuator as claimed in claim 10, wherein the substrate has an electronic element.
 15. The single-axis actuator as claimed in claim 10, wherein each of the first pair of resilient elements includes a wire electrically connected to a pad on the actuating end.
 16. The single-axis actuator as claimed in claim 10, wherein each of the first pair of resilient elements is electrically connected to a pad-anchor on the substrate.
 17. The single-axis actuator as claimed in claim 10, wherein the actuating end is a T-bar.
 18. The single-axis actuator as claimed in claim 17, wherein the T-bar is connected to the substrate through a fulcrum hinge having a first and a second sides, a first resilient element of the first pair of resilient elements is disposed on the first side of the fulcrum hinge, and a second resilient element of the first pair of resilient elements is disposed on the second side of the fulcrum hinge.
 19. The single-axis actuator as claimed in claim 18, wherein the fulcrum hinge is configured to prevent an object carried by the actuating end from peeling off from the T-bar when there is a shear force at a boundary surface between the object and the T-bar.
 20. The single-axis actuator as claimed in claim 18, wherein the driving capacitor is a comb-type driving capacitor including a fixed electrode structure fixed to the substrate and a movable electrode structure connected to the fulcrum hinge. 